Unveiling the Central Molecular Zone
with Mopra Michael Burton, Paul Jones, Maria Cunningham, Daniel Sultmann (UNSW), Andrew Walsh (Curtin), Nick Tothill (UWS), David Jones (MPIK-Heidelberg), Roland Crocker (ANU), Karl Menten, Miguel
Requena-Torres, Arnaud Belloche, Silvia Leurini (MPIfR-Bonn), Peter Schilke (Cologne), Jüergen Ott (NRAO), Jesus Martin-Pintado (CSIC/INTA) www.phys.unsw.edu.au/mopracmz
Silicon Monoxide
The Central Molecular Zone
~100 pc = 1°
Characteristic CMZ GMC
Denser n ~ 104 cm-3 n ~102 cm-3
Warmer 60K < T < 120K 10K < T < 20K
More Turbulent ΔV ~ 10–20 km/s ΔV ~ 5 km/s
Organic Species Widespread In HMCs only
CMZ vs. GMC Characteristics
Mopra 22m MM-Wave
Telescope Coonabarabran,
NSW Australia
UNSW-MOPS: 8 GHz bandwidth
spectrometer Receivers: 100 + 40 +
25 GHz bands
www.phys.unsw.edu.au/mopracmz
Data cubes publicly available
Molecular Lines Mapped in the CMZ
3mm Band: 85-93 GHz
C3H2 85.34
CH3CCH 85.46
HOCO+ 85.53
SO 86.09
H13CN 86.34
H13CO+ 86.75
SiO 86.85
HN13C 87.09
CCH 87.32 87.40
HNCO 87.93
HCN 88.63
HCO+ 89.18
HNC 90.66
HC3N 90.98
CH3CN 91.99 13CS 92.49
N2H+ 93.17
On-the-Fly-mapping 2.5° x 0.6° with 400 x 5’ grids 35” + 1 km/s resolution 7 weeks over 3 seasons 18 molecular + 2 hydrogen lines TA
*~40-80 mK per channel More data in the cubes available! The 7mm survey has another ~20 molecules and the 12mm one about 15!
G1.3 Sgr B2 Sgr A Sgr C
Complex Dynamics + Some Foreground Absorption
by Spiral Arms Check P-V diagrms below
S. Molinari et al. 2011 ApJ 735 L33
Mopra: N2H+ Peak Velocity
Herschel: Dust column density + CS velocity ranges
Coherent velocity structure along ~107 M¤ twisted molecular ring. Vrot ~ 80 km/s, r~100x60 pc Rotating ring, tracing the stable, non-intersecting x2 orbits??
Line Luminosities CO HCN HCO+ HNC
CMZ 2 x 107 2 x 105 1 x 105 6 x 104
Ratio with CO
1.0 0.1 0.06 0.03
K km/s pc2
Star Forming Galaxies: LCO ~ 5 x 108 – 2 x 1010 K km/s pc2 (Gao & Solomon 2004) LHCN/LCO ~ 0.03 – 0.2 LHCO
+/LHCN ~ 0.5 – 1.6 • CMZ Line Ratios at lower end of Starburst range
(availability of dense gas?) • CMZ Line Luminosity orders of magnitude smaller
Molecular Masses HCN HCO+ HNC Fraction
CMZ 29 9 11 100%
Sgr A 4 0.8 0.6 11%
Sgr B2 5 1 2 14%
Sgr C 2 0.4 1.5 8%
G1.3 3 0.7 1 10%
In M¤
Half the gas spread over CMZ, half in the principal dust cores. Total Molecular Mass in CMZ ~ 5 x 107 M¤ from CO
Optical Depth Corrections and [12C/13C] Isotopologue Variations
[HCO+/H13CO+]max >
[12C/13C] ~ 24
at large positive velocities
__ : Line ….: Line (tau corrected) xxx: Isotopologue ratio
Signatures of infall of more nuclear-processed gas into the Galactic centre??
40 [ 12C/ 13C
] 0
Galactic Longitude
Sgr B2 3mm (82-114 GHz) Jones et al. 2008 Sgr B2 7mm (30-50 GHz) Jones et al. 2011 CMZ 3mm (85-93 GHz) Jones et al. 2012 CMZ 7mm (42-50 GHz) Jones et al. 2013 CMZ 12mm (HOPS – 20-28 GHz) Walsh et al. 2011,
Purcell et al. 2012 CMZ CO (J=1–0 Lines) Observations need
reducing – collaborators welcome!!
For more information
Met the telescope!
Observations
Abstract. We have mapped a 2.5ox 0.5o region of the center of the Galaxy using the Mopra radio telescope in 18 molecular lines emitting from 85 to 93 GHz. This incorporates most of the region known as the Central Molecular Zone (CMZ). The molecular maps have 40 arcsec spatial resolution and 2 km s−1 spectral resolution, with emission extending to velocities of 220 km s−1. Line profiles are both very wide and complex, and do vary considerably across the CMZ. The analysis of the data has started with three different topics: To quantify the overall emission morphology, and its variation between molecules, we conducted a principal component analysis (PCA) of the integrated emission from 8 brightest species. We have selected apertures around the bright dust cores, as well as for the total region mapped, in order to study line ratio variations and to calculate optical depths so that column densities and molecule masses may be determined. We have studied the line luminosities, relative to that of CO. The luminosities are also typically 0.1-10 percent of the corresponding values that have been measured in other galaxies. The full data set, comprising the data cubes for the 20 emission lines, is publicly available for further analysis.
Rotating Disk
Peak Temperature Images from some of the stronger lines in the sample
